Abstract: The materials to be chem-milled are coated with a maskant material, a template having a specific hole pattern is then placed over the masked surface of the material. A laser beam is then directed towards the template and is scanned either manually or by numerical control means along the hole pattern. The laser is maintained at each hole for a sufficient length of time to enable the maskant to be burned from the material. The material is then chem-milled by any conventional means thereby forming holes through the material at the maskant free areas. The remaining maskant is then removed from the surface of the material.

Abstract: This process comprises the steps of depositing a suitable maskant which is resistant to the chemicals used in chem-milling on a back-up sheet such as thin plastic, punching or cutting the desired pattern to be removed from the sheet metal through the maskant and the back-up sheet, then applying the maskant by adhering the same to the sheet metal surface with the plastic back-up sheet on the outside surface. The back-up sheet/maskant combination is placed on both sides of the sheet metal where the thickness of the sheet metal requires chem-milling from both surfaces. For thin metal, one surface of the material can be directly coated with the maskant while the other surface employs the back-up sheet/maskant combination.